Preheat oven to 350F. Line an 8-by-8-inch baking pan with aluminum foil, spray with cooking spray; set aside.

To a large, microwave-safe bowl add the butter and heat to melt, about 1 minute on high power.

Wait momentarily before adding the egg so you don’t scramble it. Add the egg, brown sugar, vanilla, and whisk until smooth.

Add the flour, salt, and stir until just combined, don’t overmix.

Add the chocolate chips and stir to combine.

Turn slightly more than half the batter out into prepared pan (about 60% or so, just eyeball it so that the bottom of the pan is completely covered, albeit thin coverage); set remaining batter aside.

Evenly place the Rolos in the pan so that each Rolo is sitting on its ‘base’ rather than laying on its side. I made 6 rows of 6 Rolos each.

Drop remaining batter over the Rolos in heaping rounded tablespoons. Use a spatula to smooth the ‘blobs’ of batter together. You won’t have complete coverage and that’s okay because batter expands a bit while baking and some of the balder patches ‘grow togther’.

Bake for about 20 to 22 minutes, or until top is set in center and done; don’t overbake. Blondies firm up as they cool. A toothpick test is unreliable because you will likely hit melted chocolate or caramel, but if you hit a patch of dough, the toothpick should come out clean, or with a few moist crumbs, but no batter.

Place pan on a wire rack to cool for at least 90 minutes before slicing and serving.